This is actually a bug with the IMPORT (which IMPORTTBL uses internally). If there are other non-blank cells around the cell you're trying to import, IMPORT treats your range as a starting point instead of a start & end point.

This might actually be a feature of IMPORT instead of a bug -- I'll have to investigate further to figure out which.

We'll try to get a fix for this for at least IMPORTTBL and IMPORTMAT soon...

Ok, we changed IMPORT/WFOPEN to honor the Excel end cell specification when the end cell is the same as the first cell. This fix resolves the issue with IMPORTTBL and IMPORTMAT when trying to read in a single Excel cell.